Hydrostatic pressure dependence on the collapsing of heptamer clusters in the charge ordered spinel AlV2O4

• Published in: Solid state communications 2017-01, Vol.250, p.23-27
• Main Authors: Kalavathi, S., Vennila Raju, Selva, Chandra, Sharat, Williams, Quentin, Sahu, P.Ch
• Format: Article
• Language: English
• Subjects: A. Charge frustration; B. Spinel AlV2O4; C. Hydrostatic pressure; D. ab-initio calculations
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/j.ssc.2016.11.003

Charge frustrated spinels have engaged the interest of condensed matter studies due to the novel formation of multimer molecular sub units that lifts the degeneracy in the ground state. An exhaustive study on the stability of these molecular sub units is not available in the literature. In the present study, evidence has been obtained for the first time that hydrostatic pressure beyond 21GPa, destabilizes the vanadium heptamer molecular sub units reversibly in the unique ambient temperature charge ordered spinel AlV2O4. The bulk modulus and its pressure derivative of the charge ordered phase are constrained. In addition a systematic structural analysis as a function of temperature shows destabilization of vanadium trimers those stack up to make the heptamer units. The crystal structure and total energy have been calculated using first principles density functional formalism (GGA approximation) as a function of pressure. The results obtained corroborate the stability of the frustrated phase beyond 20GPa. •Charge-ordered spinel AlV2O4 becomes charge frustrated under hydrostatic pressure.•Transition occurs at about 21 GPa and it is reversible on decompression.•Total energy calculations confirm stability of the frustrated phase under pressure.•At high temperatures V3 trimers get disrupted leading to charge frustration.